Process and device for the continuous analysis of the composition of gases

Abstract

Process for the continuous analysis of the composition of gases, by means of a measuring head for determining the flow rate and analysis equipment which is placed a distance away from the measuring head and is connected thereto by a sample line, a calibration gas being fed to the sample line at the measuring head, by means of which the transit time of the gases is determined, and by means of this transit time a phase shift is introduced during the determination of the connection between the flow rate and the composition. According to the invention a series of calibration gas impulses are fed from the equipment, and the average transit time of the gases in the conditions prevailing locally at that moment is determined therewith, for the essentially continuous determination of the connection between the flow rate and the composition. Device for carrying out the process comprising a measuring head and analysis equipment for determining the composition of the gases, provided with a source of calibration gas in the analysis equipment, a calibration gas line connected to the sample line a short distance from the suction aperture thereof with the measuring head, means for maintaining the calibration gas under pressure, and means for periodically opening a valve in the calibration gas line, and means for determining the transit time of the calibration gas impulses through the sample line.

What is claimed is: 
     
       1. A process for continuously determining the correlation between the flow rate and the composition of gases which may fluctuate greatly and which pass through a measuring head which determines the flow rate of said gases comprising: providing a measuring head which determines the flow rate of gases, whose composition may fluctuate greatly; analyzing   the composition of said gases being analyzed using analysis equipment which is placed a distance away from the measuring head and is connected thereto by a sampling line through which it is drawn using a suction pump; providing a calibration gas for determining transit time between the measuring head and the analysis equipment being fed via a calibration gas line to the sampling line at a point near where the sampling line connects to the measuring head, said calibration gas being fed as a series of calibration gas impulses from the analyzing equipment to the sampling line via the calibration gas line; and determining the average transit time of the gases in the conditions prevailing locally at the moment using said analyzing equipment for substantially continuously determining the correlation between the flow rate and the gas composition.   
     
     
       2. A device for accurately correlating flow rate measurement data and gas composition data for a flowing gas having composition which may fluctuate greatly comprising: a measuring head through which flowing gas having a composition which may fluctuate greatly passes to be analyzed, said measuring head being provided with a volume transducer; means for continuously determining the flow rate of the flowing gas flowing through said measuring head; analysis means for determining the composition of said flowing gas; a sampling line connecting said measuring head to said analysis means; suction means for drawing said gas flowing through the measuring head to the analysis means via the sampling line; a source of pressurized calibration gas for determining the transit time between said measuring head and said analysis means; a calibration gas line for coupling said source of pressurized calibration gas to said sampling line at a juncture located near the end of said sampling line which is connected to said measuring head; a valve located in said analysis means between said source of pressurized calibration gas and said calibration gas line, said valve being operable between an open and a closed position; means for periodically opening and closing said valve at a predetermining rate to inject pressurized calibration gas impulses into said sampling line at said predetermined rate; and means for determining the transit time of said pressurized calibration gas impulses through said sampling line.   
     
     
       3. A device in claim 2, further comprising a connecting piece having first bore means which communicate with an aperture of said measuring head, said first bore means forming part of said sampling line, and having second bore means which communicate with said first bore means at a point intermediate the ends of said first bore means, said second bore means forming part of said gas calibration line. 
     
     
       4. A device according to claim 3 for analysis of human respiration air, wherein the measuring head is a mouthpiece with a built-in volume transducer, said mouthpiece capable of allowing airflow in two directions, for the inspiration and expiration of air. 
     
     
       5. A device as in claim 3, wherein said connecting piece and said first bore means are kinked. 
     
     
       6. A device according to claim 5 for analysis of human respiration air, wherein the measuring head is a mouthpiece with a built-in volume transducer, said mouthpiece capable of allowing airflow in two directions, for the inspiration and expiration of air. 
     
     
       7. A device as in claim 2, wherein said sampling line is made along at least part of its length of material which is permeable to water vapor. 
     
     
       8. A device according to claim 7 for analysis of human respiration air, wherein the measuring head is a mouthpiece with a built-in volume transducer, said mouthpiece capable of allowing airflow in two directions, for the inspiration and expiration of air. 
     
     
       9. A device according to claim 2 for analysis of human respiration air, wherein the measuring head is a mouthpiece with a built-in volume transducer, said mouthpiece capable of allowing airflow in two directions, for the inspiration and expiration of air.